Immunological and allergenic responses induced by latex fractions of Calotropis procera (Ait.) R.Br.

Immunological and allergenic responses against the latex of Calotropis procera were investigated in mice by oral and subcutaneous routes. The latex was fractionated according to water solubility and molecular size of its components. The fractions were named as non-dialyzable latex (NDL) corresponding to the major latex proteins, dialyzable latex (DL) corresponding to low molecular size substances and rubber latex (RL) which was highly insoluble in water. Anti-sera against these fractions were assayed for total IgG and IgA titration by ELISA and IgE and IgG1 were quantified by passive cutaneous anaphylaxis (PCA) in rats and mice, respectively. None of the fractions induced antibodies level increases when mice received latex fractions by oral route and thus, did not develop allergy. Nonetheless, anti-sera of mice sensitized with NDL and RL by subcutaneous route displayed considerable immunological response while DL did not. IgG level augmented consistently against NDL and RL while IgA response was detected only to NDL. NDL and RL induced very strong PCA reactions suggesting that both fractions would contain latex substances involved in allergy. Furthermore, protein analysis of NDL and RL suggests that RL still retain residual proteins abundantly found in NDL that could explain its similar allergenic effect. No IgG1 reaction was detected in any of the anti-sera tested. According to the results, the proteins of latex of Calotropis procera can provoke allergy by subcutaneous route. The NDL has previously shown to display anti-inflammatory and analgesic activities by intraperitoneal injection. It should be relevant to determine whether NDL could induce such activities when assayed by oral route since it was ineffective to induce allergy by this way.